**#include <math.h>
**

**
double fdim(double** *x***, double** *y***);
float fdimf(float**

long double fdiml(long double

These functions shall determine the positive difference between their
arguments. If *x* is greater than *y*, *x*-
*y* is returned. If *x* is less than or equal to *y*,
+0 is returned.

An application wishing to check for error situations should set *errno*
to zero and call
*feclearexcept*(FE_ALL_EXCEPT) before calling these functions.
On return, if *errno* is non-zero or
*fetestexcept*(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW)
is non-zero, an error has occurred.

Upon successful completion, these functions shall return the positive difference value.

If *x*- *y* is positive and overflows, a range error shall
occur and *fdim*(), *fdimf*(), and *fdiml*()
shall return the value of the macro HUGE_VAL, HUGE_VALF, and HUGE_VALL,
respectively.

If *x*- *y* is positive and underflows, a range error may
occur, and either ( *x*- *y*) (if representable),
or 0.0 (if supported), or an implementation-defined value
shall be returned.

If
*x* or *y* is NaN, a NaN shall be returned.

The *fdim*() function shall fail if:

- Range Error
- The result overflows.

If the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
then *errno* shall be set to [ERANGE]. If the
integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero,
then the overflow floating-point exception shall be
raised.

The *fdim*() function may fail if:

- Range Error
- The result underflows.

If the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
then *errno* shall be set to [ERANGE]. If the
integer expression (math_errhandling & MATH_ERREXCEPT) is non-zero,
then the underflow floating-point exception shall be
raised.

*The following sections are informative.*

On implementations supporting IEEE Std 754-1985, *x*- *y*
cannot underflow, and hence the 0.0 return value
is shaded as an extension for implementations supporting the XSI extension
rather than an MX extension.

On error, the expressions (math_errhandling & MATH_ERRNO) and (math_errhandling & MATH_ERREXCEPT) are independent of each other, but at least one of them must be non-zero.

*feclearexcept*() , *fetestexcept*() , *fmax*() , *fmin*()
, the Base Definitions volume of
IEEE Std 1003.1-2001, Section 4.18, Treatment of Error Conditions
for
Mathematical Functions, *<math.h>*

- NAME
- SYNOPSIS
- DESCRIPTION
- RETURN VALUE
- ERRORS
- EXAMPLES
- APPLICATION USAGE
- RATIONALE
- FUTURE DIRECTIONS
- SEE ALSO
- COPYRIGHT

Time: 21:46:01 GMT, April 16, 2011